1. Field of Invention
The present invention relates to a chemical mechanical polishing equipment. More particularly, the present invention relates to a chemical mechanical polishing equipment with at least one strip platen.
2. Description of Related Art
As semiconductor devices keep scaling down, demand for multiple-level interconnects is getting higher. Multiple-level metallization provides greater flexibility in circuit design and a substantial reduction in die size and chip cost. For integrated circuits, it is common to employ at least two to five metal layers. It is thus very important to have a planarization process on the rough surface of a wafer, so as to facilitate the manufacturing process of the multi-level interconnects and make the transferred wiring patterns more accurate. In addition, the planarization of a wafer is the major factor affecting aligning accuracy in an alignment system. If the planarization process for a wafer is poorly done, not only the mask can not accurately focus on the wafer in the alignment system, but also the error-prone probability during the manufacturing is significantly increased.
Chemical-mechanical polishing (CMP) is regarded as the only technology to provide global planarization in the manufacturing of very-large scale integrated circuits (VLSI), or even ultra-large semiconductor integration (ULSI). Essentially, CMP is based on a principle similar to a xe2x80x9cgrinding wheelxe2x80x9d in mechanical grinding and with the aid of chemical reagents, so that the rough surface of a wafer can then be smoothly ground by using this technology.
FIG. 1 is a schematic view of the conventional CMP equipment. The core elements of the CMP equipment 100 are an automated rotating polishing platen 102 and a wafer holder 104. In general, the polishing platen 102 is designed to be a round platen for the convenience of rotation with a polishing pad 106 arranged on the polishing platen 102. A provided wafer 110 is hold by the wafer holder 104 and position of the wafer holder 104 is adjustable. The wafer holder 104 can both exert force on the wafer 110 and rotate the wafer 110 independent of the rotation of the polishing platen 102. During polishing, the wafer holder 104 ensures the wafer 110 touching the polishing pad 106. A slurry supply 108 is disposed above the polishing platen and provides a polishing slurry 112 for polishing. Polishing of the wafer 110 is accomplished through the polishing pad and the polishing slurry consisting of colloidal silica. The action of polishing is both mechanical and chemical. A conditioner 114 is usually incorporated in the CMP equipment 100 for conditioning the polishing pad.
From the above arrangement shown in FIG. 1, it clearly shows that the size of round polishing platen is required to be bigger than that of the wafer, because other elements, such as, the conditioner and/or the slurry supply, are installed on or above the platen. In other words, the dimension of the CMP equipment is limited by the size of the platen, which is required to be relatively bigger than the size of the wafer. As the size of the wafer keeps increasing, the design of the conventional CMP equipment precludes further scaling down of the equipment.
Furthermore, for a standard fabrication process of forming a copper plug structure, at least two polishing pads with different selectivity are required for polishing the copper layer and the barrier layer, respectively. Therefore, it is inevitable to exchange polishing pads during the CMP process or to transfer the wafer to different polishing platens, which is the bottleneck for increasing throughput and thus leads to inefficient production line management.
It is therefore an objective of the present invention to miniaturize and scale down the CMP equipment. The design of the present invention is compatible with the existing manufacture processes. The CMP equipment of the present invention can be scaled down by using strip platens that can be smaller than the wafer size because the size for the polishing platen of the present invention needs not to completely cover the wafer for achieving global planarization. For the CMP equipment of the present invention, the layout is compact and the space is effectively utilized. Therefore, high throughput and efficient production line management can be fulfilled.
The present invention provides a CMP equipment that offers greater flexibility in performing CMP for different fabrication processes through the choices of various polishing pads and/or polishing slurry.
As embodied and broadly described herein, the invention provides a CMP equipment, comprising a wafer holder for holding a provided wafer, at least one strip polishing platen, while the strip polishing platen can be rotated about a rotation axis at the fixed end with a rotating angle less than 360 degrees, a polishing pad arranged on the polishing platen, a robotic arm coupled to the strip polishing platen and a slurry feeding system incorporated in the strip polishing platen to provide a polishing slurry for polishing.
The CMP equipment of the present invention can include one or more wafer holders, according to the requirements of the manufacture processes or other considerations. For each wafer holder of the CMP equipment, one or more strip platens can be used for achieving local planarization or global planarization. The length of the strip platens and the size of the polishing pads can be adjusted for achieving different levels of planarization. In addition, the location of the platens relative to the wafer holder and the position of the polishing pad relative to the wafer holder or relatively within the platen also should be taken into considerations.
It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed.